PERFORMANCE ANALYSIS OF FREQUENCY-HOPPED SPREAD-SPECTRUM PACKET RADIONETWORKS .2. UNSLOTTED MULTIPLE-ACCESS

This paper is concerned with the performance analysis of unslotted fre quency-hopped spread spectrum packet radio networks with Reed-Solomon forward error control coding. The following different network alternat ives are analysed in a unified manner (i) random/one-coincidence frequ ency hopping patterns, (ii) one/several code symbols per dwell interva l, (iii) independent/dependent packet arrival processes, (iv) fixed/va riable length packets. Joint probability generating functions for the pair-wise hit patterns and the effective multiple-access interference vector are determined for the different alternatives. Closed form form ulae and expressions for packet capture probabilities are readily obta ined from these generating functions. A direct proof is given that in the case of single symbol/dwell packets symbol errors, are asymptotica lly independent. Numerical results indicate that the unslotted network s outperform the corresponding slotted ones at low to moderate traffic levels, and the difference between the two networks is diminishing wh en the number of frequency bins is large.